jfs_debugfs is a program which can be used to perform various low-level
actions on a JFS formatted device.
device is the special file name corresponding to the actual device to
be edited (e.g. /dev/hdb1).
jfs_debugfs must be run as root.
a[lter]
replaces the data located at the of with
is the block number - given in decimal
is the offset within that block - given in hexadecimal
is an even-numbered string of hexadecimal digits to
write to the disk
b[tree] []
* not implemented yet *
displays one node of the btree located at of
and enters a subcommand mode to navigate the btree
SUBCOMMANDS:
l => visit left sibling
m => modify current node
p => visit parent node
r => visit right sibling
[0-9] => visit the n'th child node
x => exit subcommand mode
cb[blfsck]
displays the area used by ClearBadBlockList for communication
with fsck
SUBCOMMANDS:
m => modify entries
x => exit subcommand mode
dir[ectory] []
displays the directory entries at and enters
subcommand mode
is the directory's inode - given in decimal
currently must be zero
SUBCOMMANDS:
m => modify entries
x => exit subcommand mode
d[isplay] [ [ [ []]]]
displays objects located at the of in
is the block number - given in decimal
is the offset within - given in hexadecimal
is one of the following:
a => ascii
b => block allocation map
d => decimal
i => inode
I => inode allocation map
s => superblock
x => hexadecimal
X => extent allocation descriptor
is the number of objects to display - given in decimal
dm[ap]
displays aggregate disk (block) map
SUBCOMMANDS
m => modify map fields
f => display free count
t => display tree levels
x => exit subcommand mode
dt[ree] []
displays root of the directory btree located at
and enters a subcommand mode to navigate the btree
is the directory's inode - given in decimal
currently must be zero
SUBCOMMANDS
l => visit left sibling
m => modify current node
p => visit parent node (not parent directory)
r => visit right sibling
[0-9] => visit the n'th child node
x => exit subcommand mode
fsckw[sphdr]
displays the header of the fsck workspace in the aggregate
SUBCOMMANDS:
m => modify entries
x => exit subcommand mode
h[elp] []
displays help for
if no command is given, all possible commands are displayed
ia[g] [] [a | s | ]
displays IAG information for and enters subcommand
mode
is given in decimal
a is to use the primary aggregate inode table
s is to use the secondary aggregate inode table
currently must be zero
SUBCOMMANDS
e => display/modify inode extents map
m => modify IAG
p => display/modify persistent map
w => display/modify working map
x => exit subcommand mode
i[node] [] [a | s | ]
displays inode information for and enters sub‐
command mode
is given in decimal
a is to use the primary aggregate inode table
s is to use the secondary aggregate inode table
currently must be zero
SUBCOMMANDS
a => display/modify inode's ACL
m => modify inode
x => exit subcommand mode
logs[uper]
displays the journal log superblock and enters subcommand mode
SUBCOMMANDS
m => modify journal log superblock
x => exit subcommand mode
q[uit]
exits jfs_debugfs
se[t] []
* not implemented yet *
set user-defined to
if no arguments are given, displays all set variables
must begin with an alphabetic character
su[perblock] [p | s]
displays superblock data
p displays the primary superblock
s displays the secondary superblock
SUBCOMMANDS:
m => modify entries
x => exit subcommand mode
s2p[erblock] [p | s]
displays alternate superblock data
p displays the primary superblock
s displays the secondary superblock
SUBCOMMANDS:
m => modify entries
x => exit subcommand mode
u[nset]
* not implemented yet *
deletes user-defined
xt[ree] []
displays root of the non-directory btree located at and enters a subcommand mode to navigate the btree
is the directory's inode - given in decimal
currently must be zero
SUBCOMMANDS
l => visit left sibling
m => modify current node
p => visit parent node (not parent directory)
r => visit right sibling
[0-9] => visit the n'th child node
x => exit subcommand mode
If you find a bug in JFS or jfs_debugfs, please report it via the bug
tracking system ("Report Bugs" section) of the JFS project web site:
http://jfs.sourceforge.net/
Please send as much pertinent information as possible, including the
complete output of running jfs_fsck with the -v and -n options on the
JFS device.
Barry Arndt (barndt@us.ibm.com)
William Braswell, Jr.
jfs_debugfs is maintained by IBM.
See the JFS project web site for more details:
http://jfs.sourceforge.net/
October 29, 2002 jfs_debugfs(8)
